TERMS
Number of bits that determine the amount of precision in digitizing the analog signal and therefore the number of shades of gray that can be displayed in an image.
Bit Depth
A pixel that has an 8-bit depth displays how many shades of gray?
256
If you decrease the pixel size, how does this affect the spatial resolution?
Increases spatial resolution
Give TWO terms
Turbid and unstructured
Which layer is first in a DIRECT flat panel system?
A. Amorphous Silicon
B Amorphous Selenium
C TFT
B - Amorphous Selenium
This can be defined by the unity of lines pairs per millimeter (lp/mm)
spatial frequency
What is the binary number of 896
1110000000.
1 1 1 0 0 0 0 0 0 0
29 28 27 26 25 24 23 22 21 20
1-23-7-14-25-56-112-224-448-896
What effect does insufficient mAs have on the SNR?
A Increases the SNR
B Has no effect on SNR
C Decreases SNR
C Decreases the Signal to Noise Ratio
What is a common phosphor for a CR imaging plate?
Barium Flourohalide bromides with europium
Barium Fluorohalided iodides with europium
What is performed if there is suspected damage to an flat panel detector?
Panel autopsy
This is the measurement of the efficiency of an IR in converting the x-ray exposure it receives to a quality radiographic image.
DQE or Detective Quantum Efficiency
What is the decimal number of the binary #101010?
42
15 04 13 02 11 00
32 0 8 0 2 0 = 42
Within each DEL there is an area for a capacitor, a TFT, and a capture area. How is the percentage of capture area described and how does its size influence spatial resolution?
Fill factor
Increased fill factor means increase spatial resolution
What percentage of the latent image is lost if the CR image plate is not read within 8 hours?
25%
____________ works by sensing the presence of radiation during the first 1-2 milliseconds of the x-ray exposure. In order to sense the presence of radiation, a small charge is placed on the FTF in preparation for the exposure by an on-board battery or capacitor.
Auto Detection or Trigger Panel
This is used to recognize the clinically useful area on the imaging plate so it is the only data that will be manipulated and it eliminates the signal from outside the collimated field.
Exposure Field Recognition or Exposure Data Recognition.
You used 30 mAs for a shoulder on the upright bucky for Mr. Smith prior to surgery. TheEI number was 1700. You need to do a post op image with out a grid. What is the new technique that you will use
This is underexposed. To get the EI# to normal - the technique would need to be doubled (60).
For the post op pic we are now going from a grid to non grid situation. mAs1/mAs2= GCF1/GCF2
12:1 = 5 No Grid = 1 NEW MAS = 60/5 = 12
Which digital system has the highest DQE?
A - Film
B - CR
C - DR
D - All have the same
C - DR has the best DQE
Indirect is better than direct
In CR, if the reader scanning frequency and the radiographic grid frequency are similar and in the same orientation, what is likely to occur?
Moire effect
In a digital image systems, an electrical charge is briefly stored in what areas? (Hint - there are two types of direct systems)
CCD and TFT
This is capable of converting x-rays directly into an electrical signal. An example of this is Amorphous Selenium
Photoconductor
After taking the image my DI come's up as -2. I used 6 mAs to start. What is my correction
The new mAs should be 24
6 + 25% = 7.5 (-1)
7.5 + 25% = 9.5 (0)
True or False
Maximum spatial frequency is equal to the Nyquist Theory
True -The more the signal is sampled, the more information is obtained, the smaller the pixels can be. The downside is that the scan time will take longer
The CR image plate requires _____ of exposure to produce an optimal image.
a. 0.1 mGy
b. 10 mGy
c. 0.01 mGy
d. 1 mGy
C
In a DR system, there are two classification of detectors. What are they?
portable and integral